Revolutionizing Laser Technology: The Chip-Scale Titanium-Sapphire Laser
As lasers go, those made of Titanium-sapphire (Ti:sapphire) are considered to have “unmatched” performance. They are indispensable in many fields, including cutting-edge quantum optics, spectroscopy, and neuroscience. But that performance comes at a steep price. Ti:sapphire lasers are big, on the order of cubic feet in volume. They are expensive, costing hundreds of thousands of dollars each. And they require other high-powered lasers, themselves costing $30,000 each, to supply them with enough energy to function.
Despite their incredible capabilities, Ti:sapphire lasers have never achieved the broad, real-world adoption they deserve – until now. In a groundbreaking development in scale, efficiency, and cost, researchers at Stanford University have created a Ti:sapphire laser on a chip. This prototype is four orders of magnitude smaller (10,000x) and three orders of magnitude less expensive (1,000x) than any Ti:sapphire laser ever produced.
“This is a complete departure from the old model,” said Jelena Vu?kovi?, the Jensen Huang Professor in Global Leadership, a professor of electrical engineering, and the senior author of the paper introducing the chip-scale Ti:sapphire laser published in the journal Nature. “Instead of one large and expensive laser, any lab might soon have hundreds of these valuable lasers on a single chip. And you can fuel it all with a simple green laser pointer.”
Profound benefits
“When you leap from tabletop size and make something producible on a chip at such a low cost, it puts these powerful lasers in reach for a lot of different important applications,” said Joshua Yang, a doctoral candidate in Vu?kovi?’s lab and co-first author of the study, along with Vu?kovi?’s Nanoscale and Quantum Photonics Lab colleagues, research engineer Kasper Van Gasse, and postdoctoral scholar Daniil M. Lukin.
In simple terms, gain bandwidth translates to the broader range of colors the laser can produce compared to other lasers. It’s also ultrafast, with pulses of light issuing forth every quadrillionth of a second.
The new chip-scale Ti:sapphire laser is a game-changer in terms of size, portability, cost, and efficiency. With no moving parts and the ability to be mass-produced, this breakthrough technology has the potential to democratize the use of Ti:sapphire lasers across various industries.
How it’s done
To create the chip-scale Ti:sapphire laser, the researchers started with a bulk layer of Titanium-sapphire on a silicon dioxide platform, all resting on true sapphire crystal. By grinding, etching, and polishing the Ti:sapphire to an extremely thin layer and patterning it with tiny ridges, they created a waveguide that guides the light around and around, intensifying its power.
Essentially, by reducing the area in which the power is concentrated, the intensity of the laser is significantly increased, making it more efficient. A microscale heater is used to tune the color of the light emitted, ranging from 700 to 1,000 nanometers.
Spotlight on applications
Vu?kovi?, Yang, and their colleagues are excited about the wide range of fields that the chip-scale Ti:sapphire laser could transform. From advancing quantum computing to revolutionizing neuroscience with optogenetics, the possibilities are endless. Additionally, in ophthalmology, the laser could enhance laser surgery techniques and retinal health assessments with its compact and cost-effective design.
The team is currently working on perfecting the chip-scale Ti:sapphire laser and finding ways to mass-produce them on wafers. With the potential to fit thousands of lasers on a single 4-inch wafer, the cost per laser is set to become almost zero, making this technology truly groundbreaking.